The problem of stabilizing peroxide compounds (e.g. hydrogen peroxide) in aqueous solutions employed in bleaching of cellulose fiber is well known in the art. Various expedients, including use of diethylene triamine penta(methylene phosphonic acid) and its water soluble salts have been proposed, e.g. in U.S. Pat. No. 3,860,391 issued Jan. 14, 1975 to A. Kling et al., the disclosure of which is incorporated herein by reference. Such expedients have provided substantial improvements in peroxide stabilization but it is desirable to further increase such stability, e.g. to lower the amount of peroxide consumed in bleaching a given amount of cellulose fiber, to facilitate holding constant the conditions under which the bleaching is carried out, etc.
Accordingly, it is an object of this invention to provide an improvement of such a process whereby stability of peroxide in the bleaching solution is substantially increased. Another object is improvement of peroxide stability in bleaching solutions essentially free of the silicates which are commonly used to enhance such stability but tend to cause or aggravate other problems in the bleaching operation such as precipitates that result in fabric abrasion, uneven dyeing and finishing, etc. Another object is improved peroxide stability in the hard waters from which such solutions are typically prepared for commercial-scale bleaching. Still another object is provision of a storage-stable composition which may be conveniently added to such solutions to enhance peroxide stability therein. These and other objects will be further apparent from the following disclosure in which percentages are by weight except where otherwise noted.